It's been the gigantic, messy elephant in the room since Carol Peletier (Melissa McBride) and Tyreese (Chad Coleman) joined forces: Back at the beginning of The Walking Dead Season 4, Carol killed Tyreese's girlfriend, Karen, by stabbing her in the temple. She had her reasons, of course. Karen was one of the first of Team Prison to come down with the flu that threatened to wipe them all out; by stabbing Karen and another survivor, then burning their bodies, Carol was trying to keep the virus from spreading. She figured they were going to die anyway, so might as well make it quick and painless — while keeping the other survivors alive.

When the gang discovered the burnt corpses, however, Tyreese was ready for blood. A few episodes later, after weeks of rampant speculation, Carol finally confessed to Rick Grimes (Andrew Lincoln) that she did the deed. In response, Rick banished her from the group… but he didn't tell Tyreese the news.

Warning: other MAJOR episode spoilers for Season 4, Episode 14: "The Grove" ahead!

In Season 4, Episode 14: "The Grove," Carol finds the perfect time to come clean about that little bit of info — but it's after she and Tyreese have to make a tough call of their own. When Lizzie Samuels (Brighton Sharbino) kills her little sister Mika Samuels (Kyla Kenedy) and sees nothing wrong with her actions, Tyreese asks Carol if Lizzie did it. Carol says no — "She would have let them turn." Lizzie, after all, thinks of the Walkers as human beings.

After Carol makes the tough decision to take Lizzie out — and does the deed — Carol confesses that she killed Karen in order to protect the group. She slides her gun over to Tyreese so he can get his revenge… but instead, he asks if Karen had a quick death. When Carol says she did, Tyreese forgives her — sort of. "I'm never gonna forget. It happened," he says. "But I forgive you."

Carol and Tyreese move on together with baby Judith the next day, and it seems like Tyreese has mostly forgiven Carol — but we wouldn't be surprised if we haven't seen the last of this tension between the two.

The Walking Dead airs Sunday nights at 9 p.m. on AMC.